Methods and systems for detecting and recovering from control instability caused by impeller stall in a chiller system are provided. In one embodiment, an impeller stall detection and recovery component of a chiller control unit calculates a control error signal frequency spectrum for an evaporator leaving water temperature, determines whether a high frequency signal content of the control error signal frequency spectrum exceeds acceptable limits, and adjusts a surge boundary control curve downward by a predetermined incremental value in order to resolve instability caused by impeller stall.

An arrangement includes a vacuum pump having a rotor, and a drive unit for driving the rotor and having at least one magnetic interference field-generating component and at least one compensation coil for compensating the magnetic interference field generated by the at least one component.

An object of the present invention is to improve, using a simple configuration, heat dissipation of a regenerative resistor that is disposed in a vacuum pump control device (controller) connected to a vacuum pump. The regenerative resistor disposed in the vacuum pump control device is stored in an aluminum die-cast casing. More concretely, a housing of the vacuum pump control device is prepared by aluminum die casting (metal mold casting). A regenerative resistor storing portion (aluminum die-cast casing) provided with a hollow portion is provided on a top panel of the aluminum die cast, the hollow portion being designed to have a size accommodating the entire regenerative resistor. The regenerative resistor is fitted into the hollow portion, and an opening section of the hollow portion is sealed with an aluminum sheet of the same material as that of the casing. In this manner, the regenerative resistor can removably be stored in the aluminum die-cast casing.

A turbo blower operable in a surge area and, more particularly, a turbo blower operable in a surge area is provided. The turbo blower increases consistency of performance thereof and efficiency by preventing suspension thereof due to a temporarily generated surge by operating even in a surge area for a predetermined time in addition to a normal area in which the turbo blower normally operates.

A safety device for a vehicle can include an impulse sensor configured to sense an impact to the vehicle and generate an impulse signal based on the impact, a compressor configured to compress refrigerant for a refrigeration cycle of the vehicle, and a safety valve connected to the compressor and configured to receive the impulse signal from the impulse sensor, and in response to the impulse signal exceeding a predetermined value, open the safety valve to place an inner space of the compressor in communication with an outside of the compressor for discharging the refrigerant outside the vehicle.

Provided are a vacuum pump and a method for the vacuum pump in which, when contact between a rotating body and a stator is sensed, the cause of the contact can be analyzed. Contact determination is made using a threshold for rotating body contact determination for a displacement signal and a threshold for rotating body contact determination for an acceleration signal. The amount of unbalance of a rotating body is determined using a threshold for amount-of-unbalance increase determination for the displacement signal and a threshold for amount-of-unbalance increase determination for the acceleration signal. When, in one of the displacement signal and the acceleration signal, the threshold for amount-of-unbalance increase determination or the threshold for amount-of-unbalance increase determination is exceeded within a predetermined time before determination of an estimated time point of contact, the contact is determined not to be caused by an increase in accumulation of products.

A seal includes a mating ring that rotates relative to a carbon primary ring at a seal interface. A buffer gas is provided into the seal and passes from the back of the primary ring to the seal interface. The seal can be used as a separation seal or in combination with another seal.

A vacuum pump device comprises: a power supply device including a dew condensation detector configured to detect dew condensation, a regenerative braking resistance, and a controller configured to energize the regenerative braking resistance; a cooling system using coolant; and a pump main body including a motor rotatably driven by the power supply device. When the dew condensation detector detects the dew condensation, the controller energizes the regenerative braking resistance to heat an inside of the power supply device.

A system and method for rapid pressurization of a motor compartment and cooling system during a shutdown, a surge, and/or other situations in which the suction pressure significantly varies. A motor/compressor arrangement includes a seal gas system fluidly communicating with the motor compartment via a motor pressurization line, with the outlet of the compressor, and with a shaft seal. A motor pressurization valve is coupled to the motor pressurization line and a controller is configured to open the motor pressurization valve at start-up of the motor-compressor to supply seal gas to the motor compartment and to pressurize the motor compartment when a difference between the seal gas supply pressure and the suction pressure is indicative of the seal gas supply pressure being insufficient.

An actuation system is provided for varying the pitch of the blades of a variable pitch fan or propeller. The actuation system includes a first actuator and a second actuator. The actuation system further includes a first linkage which operably connects the first actuator to the blades such that operation of the first actuator varies the pitch of the blades via the first linkage. The actuation system further includes a second linkage which operably connects the second actuator to the first actuator such that operation of the second actuator varies the pitch of the blades by series connection of the second linkage to the first linkage.